#include <iostream>

using namespace std;

/// Definition for a binary tree node.
struct TreeNode {
    int val;
    TreeNode *left;
    TreeNode *right;
    TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};

class Solution {
public:
    int maxDepth(TreeNode* root) {

        if( root == NULL )
            return 0;

        return 1 + max( maxDepth(root->left) , maxDepth(root->right) );
    }
};

int main() {

    return 0;
}